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Energy Bunching from Subcycle Ionization Injection in Laser Wakefield Acceleration
A Angella1, E Löfquist1, C Gustafsson1
1Lund University, Department of Physics, P.O. Box 118, SE-22100 Lund, Sweden.
Physical Review Letters
|March 1, 2026
Summary
Researchers observed carrier-envelope phase-driven energy bunching in laser wakefield acceleration. This breakthrough enables subfemtosecond control over electron beams synchronized to laser waveforms.
Area of Science:
- Plasma Physics
- Laser-Particle Acceleration
Background:
- Laser wakefield acceleration (LWFA) is a promising technique for generating high-energy electron beams.
- Precise control over electron beam properties, such as energy and bunching, is crucial for advanced applications.
- The carrier-envelope phase (CEP) of intense laser pulses influences plasma dynamics but has been challenging to control in LWFA.
Purpose of the Study:
- To experimentally demonstrate carrier-envelope phase-driven energy bunching in LWFA.
- To investigate the mechanism of electron trapping and beam structuring synchronized to the laser field.
- To explore the potential for attosecond control in plasma acceleration.
Main Methods:
- Utilized a few-cycle (∼9 fs), multiterawatt laser pulse.
- Employed ionization injection in a helium-nitrogen gas mixture.
- Analyzed electron spectra for quasimonoenergetic peaks and energy spacing.
Main Results:
- Observed electron spectra with multiple quasimonoenergetic peaks.
- Demonstrated regular, narrow energy spacing between these peaks.
- Attributed the observed comb structure to intermittent trapping influenced by the evolving CEP.
Conclusions:
- Established the first experimental observation of CEP-driven energy bunching in LWFA.
- Showcased subcycle ionization injection as a method for attosecond control.
- Enabled synchronized trapping and beam structuring on subfemtosecond timescales.
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